1. Field of the Invention
This invention relates to a chemical method of decreasing nitric oxide, NO.sub.x, levels, and more particularly to a composition of matter for reducing NO.sub.x levels in diesel fuels.
2. Description of Related Information
Nitrogen oxides are the oxidation products of elemental nitrogen, organic, or inorganic nitrogen and oxygen at elevated temperatures. Nitrogen oxides include: nitric oxide, NO; nitrogen dioxide, NO.sub.2 ; nitrogen trioxide, NO.sub.3 ; dinitrogen trioxide, N.sub.2 O.sub.3 ; tetranitrogen pentaoxide, N.sub.4 O.sub.5 ; tetranitrogen hexaoxide, N.sub.4 O.sub.6 ; nitrous oxide, N.sub.2 O; and the like. The elevated temperatures required to prepare these nitrogen oxidation products are routinely obtained in internal combustion engines utilizing gasoline, diesel, or aviation fuel, and the NO.sub.x, pollution from internal combustion engines continues to be a significant problem today.
There are very strong ecological and environmental reasons to reduce or eliminate NO.sub.x as an internal combustion oxidation product. For example, NO.sub.x is directly responsible for acid rain and photochemical smog. Moreover, chronic exposure to NO.sub.x has been directly linked with restricted pulmonary compliance in non-smoking healthy males and to acute respiratory disease among children living in "high exposure" towns in Czechoslovakia. NO.sub.x has also been identified as a key irritant cited for the high incidence of chronic bronchitis among Japanese postal workers servicing urban centers as outlined in Medical and Biologic Effects of Environmental Pollutants by the National Academy of Sciences, 1977.
Many physical methods have been suggested to reduce or eliminate. For example, U.S. Pat. No. 3,894,141 describes reacting NO.sub.x with liquid hydrocarbons; U.S. Pat. No. 4,405,587 describes burning NO.sub.x with a hydrocarbon at high temperature; U.S. Pat. No. 4,448,899 describes reacting NO.sub.x with an iron chelate; U.S. Pat. No. 3,262,751 describes reacting NO.sub.x with a conjugated diolefin; and U.S. Pat. No. 3,900,554 describes reacting a combination of ammonia and oxygen with nitric oxide. A drawback of these techniques is that they can involve a great deal of capital outlay and require major consumption of additives, and scrubbers, etc. Another drawback is that the reactions described can create organic pollutant disposal problems, and ammonia disposal problems, as well as create toxic and malodorous environments. Further drawbacks are that they require the presence of oxygen and are relatively expensive. Finally, these methods also require controlled environments which make them impractical if not impossible to use in mobile vehicles.
An object of the present invention is to provide an economical means for reducing NO.sub.x in diesel exhaust. A further object of the present invention is to provide a means for reducing NO.sub.x in diesel exhaust which can be used in a motor vehicle. A further objective of the present invention is to provide a chemical composition which can be added to diesel fuel to achieve reduction of NO.sub.x in diesel exhaust.
Back et al., Can. J. Chem. 46,531 (1968), discloses the effect of nitric oxide on the photolysis of isocyanic acid, HNCO, the decomposition product of cyanuric acid. An increase of nitrogen concentration in the presence of large amounts of nitric oxide was observed when nitric oxide came in contact with isocyanic acid or the photolysis product of HNCO. The increased concentration of nitrogen was attributed by the authors directly to nitric oxide level reduction.
Furthermore, use of cyanuric acid as a source of isocyanic acid for purposes of studying various properties of the latter or its subsequent degradation products is well known in the art. See, for example, Okable, J. Chem. Phys., 53, 3507 (1970) and Perry, J. Chem. Phys. 82,5485 (1985).